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crosvm/media/ffmpeg
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Alexandre Courbot ae02641b1b media: ffmpeg: allow zero-copy for input packets 
Add a wrapper for libavcodec's AVBufferRef and allow AvPacket to be
built from one ; this makes the AvPacket the owner of the data and means
it doesn't need to internally copy it.

The input data will be dropped once avcodec signals that it doesn't need
it anymore.

BUG=b:169295147
TEST=v4l2r's simple_decoder can decode a H.264 stream.

Change-Id: I9fa54124daed031fd1f397eaa8d57dc73f83c9b8
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3782037
Reviewed-by: Takaya Saeki <takayas@chromium.org>
Tested-by: Alexandre Courbot <acourbot@chromium.org>
Commit-Queue: Alexandre Courbot <acourbot@chromium.org>
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
2022-07-30 02:52:32 +00:00
..
src media: ffmpeg: allow zero-copy for input packets 2022-07-30 02:52:32 +00:00
bindgen.sh
build.rs
Cargo.toml
README.md
VERSIONS

README.md

FFmpeg wrapper

This is a minimal FFmpeg 4.4 wrapper for use with the virtio-video device, allowing to run a virtual video device backed by software decoding or encoding. This is useful for development and testing in situations where no supported video acceleration is available on the host.

Although several FFmpeg binding crates exist, most of them are not able to link against the system FFmpeg, and the only one that does is released under a software license that makes our lawyers nervous. Also they all run bindgen at build time, which is not possible to do under the Chrome OS build system and would require to patch the crate with fully generated bindings.

So taking this in consideration, as well as the extra work that it is to depend on external Rust crates in Chrome OS, it is preferable to add our own simple bindings here that cover just the parts of FFmpeg that we need.

This crate has minimal dependencies ; on the FFmpeg side, it just uses libavcodec, libavutil and libswscale.

The bindings can be updated using the bindgen.sh script. A few elements that bindgen cannot generate because they are behind C macros are re-defined in avutil.rs and error.rs, as well as tests to ensure their correctness.

And that's about it.